Basis of Presentation and Consolidation and Recently Issued Accounting Standards (Notes)	9 Months Ended
Jun. 30, 2016
Basis of Presentation and Consolidation [Abstract]
Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]	Basis of Presentation and Consolidation and Recently Issued Accounting Standards INTL FCStone Inc., a Delaware corporation, and its consolidated subsidiaries (collectively “INTL” or “the Company”), form a diversified, global financial services organization providing financial products and advisory and execution services to help clients access market liquidity, maximize profits and manage risk. The Company’s services include comprehensive risk management advisory services for commercial customers; execution of listed futures and options on futures contracts on all major commodity exchanges; structured over-the-counter (“OTC”) products in a wide range of commodities; physical trading and hedging of precious metals and select other commodities; trading of more than 150 foreign currencies; market-making in international equities; fixed income; debt origination and asset management. The Company provides these services to a diverse group of more than 20,000 accounts, representing approximately 11,000 consolidated clients located throughout the world, including producers, processors and end-users of nearly all widely-traded physical commodities to manage their risks and enhance margins; to commercial counterparties who are end-users of the firm’s products and services; to governmental and non-governmental organizations; and to commercial banks, brokers, institutional investors and major investment banks. Basis of Presentation and Consolidation The accompanying condensed consolidated balance sheet as of September 30, 2015, which has been derived from audited financial statements, and the unaudited interim condensed consolidated financial statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Certain information and note disclosures normally included in annual financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) have been condensed or omitted pursuant to those rules and regulations. The Company believes that the disclosures made are adequate to make the information presented not misleading. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation of the condensed consolidated financial statements for the interim periods presented have been reflected as required by Rule 10-01 of Regulation S-X. Operating results for interim periods are not necessarily indicative of the results that may be expected for the full year. It is suggested that these interim condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and related notes contained in the Company’s Form 10-K for the fiscal year ended September 30, 2015 filed with the SEC. These condensed consolidated financial statements include the accounts of INTL FCStone Inc. and all other entities in which the Company has a controlling financial interest. All material intercompany transactions and balances have been eliminated in consolidation. The Company’s fiscal year end is September 30, and the fiscal quarters end on December 31, March 31, June 30 and September 30. Unless otherwise stated, all dates refer to fiscal years and fiscal interim periods. The preparation of condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent liabilities as of the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. The most significant of these estimates and assumptions relate to fair value measurement for financial instruments and investments, revenue recognition, the provision for potential losses from bad debts, valuation of inventories, valuation of goodwill and intangible assets, self-insurance liabilities, incomes taxes and contingencies. Although these and other estimates and assumptions are based on the best available information, actual results could be materially different from these estimates. In the condensed consolidated income statements, the total revenues reported combine gross revenues for the physical commodities business and net revenues for all other businesses. The subtotal ‘operating revenues’ in the condensed consolidated income statements is calculated by deducting physical commodities cost of sales from total revenues. The subtotal ‘net operating revenues’ in the condensed consolidated income statements is calculated as operating revenues less transaction-based clearing expenses, introducing broker commissions and interest expense. Transaction-based clearing expenses represent variable expenses paid to executing brokers, exchanges, clearing organizations and banks in relation to our transactional volumes. Introducing broker commissions include commission paid to non-employee third parties that have introduced customers to the Company. Net operating revenues represent revenues available to pay variable compensation to risk management consultants and traders and direct non-variable expenses, as well as variable and non-variable expenses of operational and administrative employees. Change in Precious Metals Accounting The Company engages in trading activities in a variety of physical commodities, including actively trading precious metals whereby the Company provides a full range of trading and hedging capabilities, including OTC products, to select producers, consumers, and investors. In the Company’s precious metals trading activities, it acts as a principal, committing its own capital to buy and sell precious metals on a spot and forward basis. On April 10, 2015 (the “transfer date”), the Company transitioned the portion of its precious metals business conducted through its unregulated domestic subsidiary, INTL Commodities Inc., to its United Kingdom based broker-dealer subsidiary, INTL FCStone Ltd. INTL FCStone Ltd is regulated by the Financial Conduct Authority (“FCA”), the regulator of the financial services industry in the United Kingdom. In anticipation of the transfer of the precious metals business, INTL Commodities Inc. liquidated all of its precious metals inventory as of the transfer date. Subsequent to the transfer, precious metals inventory held by INTL FCStone Ltd. is measured at fair value, with changes in fair value included as a component of ‘trading gains, net’ on the condensed consolidated income statement, in accordance with U.S. GAAP accounting requirements for broker-dealers. Precious metals inventory held by subsidiaries that are not broker-dealers continues to be valued at the lower of cost or market value. Prior to the transfer, INTL Commodities Inc. precious metals sales and costs of sales were recorded on a gross basis in accordance with the Revenue Recognition Topic of the Accounting Standards Codification (“ASC”). Subsequent to the transfer, INTL FCStone Ltd. precious metals sales and cost of sales are presented on a net basis and included as a component of ‘trading gains, net’ on the condensed consolidated income statements, in accordance with U.S GAAP accounting requirements for broker-dealers. Precious metals sales and cost of sales for subsidiaries that are not broker-dealers continue to be recorded on a gross basis. The change had no effect on the Company’s operating revenues, income before tax, or net income. Management has historically assessed the performance of the physical commodities businesses on an operating revenues basis, and continues to do so. Recent Accounting Pronouncements In June 2016, the FASB issued new accounting guidance for recognition of credit losses on financial instruments, which is effective January 1, 2020, with early adoption permitted on January 1, 2019. The guidance introduces a new credit reserving model known as the Current Expected Credit Loss (“CECL”) model, which is based on expected losses, and differs significantly from the incurred loss approach used today. The CECL model requires measurement of expected credit losses not only based on historical experience and current conditions, but also by including reasonable and supportable forecasts incorporating forward-looking information and will likely result in earlier recognition of credit reserves. The Company is currently evaluating the impact the new guidance will have on its financial position, results of operations and cash flows. In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (ASU) 2014-09, “Revenue from Contracts with Customers (Topic 606).” ASU 2014-09 completes the joint effort by the FASB and International Accounting Standards Board (IASB) to improve financial reporting by creating common revenue recognition guidance for GAAP and International Financial Reporting Standards (IFRS). In March 2016, the FASB issued ASU 2016-08, “Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net).” ASU 2016-08 clarifies the implementation guidance on principal versus agent considerations. In April 2016, the FASB issued ASU 2016-10, “Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing.” ASU 2016-10 clarifies the implementation guidance on identifying performance obligations. These ASUs apply to all companies that enter into contracts with customers to transfer goods or services. These ASUs are effective for public entities for interim and annual reporting periods beginning after December 15, 2017. Early adoption is permitted only as of annual reporting periods beginning after December 15, 2016, including interim periods within that reporting period. The Company expects to adopt this guidance starting with the first quarter of fiscal year 2019. Entities have the choice to apply these ASUs either retrospectively to each reporting period presented or by recognizing the cumulative effect of applying these standards at the date of initial application and not adjusting comparative information. The Company is currently evaluating the requirements of these standards and has not yet determined the impact on our condensed consolidated financial statements. In March 2016, the FASB issued ASU 2016-09, “Compensation – Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting.” ASU 2016-09 simplifies the accounting for share-based payment award transactions including: income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. ASU 2016-09 is effective for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years. Early adoption is permitted. The Company expects to adopt this guidance starting with the first quarter of fiscal year 2018. The Company is currently evaluating the requirements of ASU 2016-09 and has not yet determined the impact on our condensed consolidated financial statements. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), which supersedes ASC 840, Leases. This ASU is based on the principle that entities should recognize assets and liabilities arising from leases. The ASU does not significantly change the lessees’ recognition, measurement and presentation of expenses and cash flows from the previous accounting standard. The ASU’s primary change is the requirement for entities to recognize a lease liability for payments and a right of use asset representing the right to use the leased asset during the term on operating lease arrangements. Lessees are permitted to make an accounting policy election to not recognize the asset and liability for leases with a term of twelve months or less. Lessors’ accounting under the ASC is largely unchanged from the previous accounting standard. In addition, the ASU expands the disclosure requirements of lease arrangements. Lessees and lessors will use a modified retrospective transition approach, which includes a number of practical expedients. This guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. The Company expects to adopt this guidance starting with the first quarter of fiscal year 2020. The Company has not determined the potential effects on the condensed consolidated financial statements. In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments--Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. ASU No. 2016-01 addresses the recognition, measurement, presentation and disclosure of financial assets and liabilities. The guidance primarily affects the accounting for equity investments, financial liabilities under the fair value option and the presentation and disclosure requirements for financial instruments. In addition, the guidance clarifies the valuation allowance assessment when recognizing deferred tax assets resulting from unrealized losses on available-for-sale debt securities. This guidance is effective for the Company in the first quarter of fiscal 2019, and early adoption is not permitted, with certain exceptions. The amendments are required to be applied by means of a cumulative-effect adjustment on the balance sheet as of the beginning of the fiscal year of adoption. The Company is currently assessing the impact, if any, the guidance may have upon adoption. In April 2015, the FASB issued ASU No. 2015-03, Interest – Imputation of Interest (Subtopic 835-30). ASU 2015-03 requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability. In June 2015, the FASB issued ASU 2015-15 as an amendment to this guidance to address the absence of authoritative guidance for debt issuance costs related to line-of-credit arrangements. The SEC staff stated that they would not object to an entity deferring and presenting debt issuance costs as an asset and subsequently amortizing the deferred debt issuance costs ratably over the term of the line-of-credit arrangement, regardless of whether there are any outstanding borrowings on the line-of-credit arrangement. The ASU is effective for public entities for annual periods beginning after December 15, 2015, and interim periods within those annual reporting periods. Early adoption is permitted for financial statements that have not been previously issued. The guidance will be applied on a retrospective basis. The Company expects to adopt this guidance starting with the first quarter of fiscal year 2017. The adoption of this standard is not expected to have a material impact on the condensed consolidated financial statements.

Basis of Presentation and Consolidation and Recently Issued Accounting Standards

INTL FCStone Inc., a Delaware corporation, and its consolidated subsidiaries (collectively “INTL” or “the Company”), form a diversified, global financial services organization providing financial products and advisory and execution services to help clients access market liquidity, maximize profits and manage risk. The Company’s services include comprehensive risk management advisory services for commercial customers; execution of listed futures and options on futures contracts on all major commodity exchanges; structured over-the-counter (“OTC”) products in a wide range of commodities; physical trading and hedging of precious metals and select other commodities; trading of more than 150 foreign currencies; market-making in international equities; fixed income; debt origination and asset management.

The Company provides these services to a diverse group of more than 20,000 accounts, representing approximately 11,000 consolidated clients located throughout the world, including producers, processors and end-users of nearly all widely-traded physical commodities to manage their risks and enhance margins; to commercial counterparties who are end-users of the firm’s products and services; to governmental and non-governmental organizations; and to commercial banks, brokers, institutional investors and major investment banks.

Basis of Presentation and Consolidation

The accompanying condensed consolidated balance sheet as of September 30, 2015, which has been derived from audited financial statements, and the unaudited interim condensed consolidated financial statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Certain information and note disclosures normally included in annual financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) have been condensed or omitted pursuant to those rules and regulations. The Company believes that the disclosures made are adequate to make the information presented not misleading. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation of the condensed consolidated financial statements for the interim periods presented have been reflected as required by Rule 10-01 of Regulation S-X.

Operating results for interim periods are not necessarily indicative of the results that may be expected for the full year. It is suggested that these interim condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and related notes contained in the Company’s Form 10-K for the fiscal year ended September 30, 2015 filed with the SEC.

These condensed consolidated financial statements include the accounts of INTL FCStone Inc. and all other entities in which the Company has a controlling financial interest. All material intercompany transactions and balances have been eliminated in consolidation.

The Company’s fiscal year end is September 30, and the fiscal quarters end on December 31, March 31, June 30 and September 30. Unless otherwise stated, all dates refer to fiscal years and fiscal interim periods.

The preparation of condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent liabilities as of the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. The most significant of these estimates and assumptions relate to fair value measurement for financial instruments and investments, revenue recognition, the provision for potential losses from bad debts, valuation of inventories, valuation of goodwill and intangible assets, self-insurance liabilities, incomes taxes and contingencies. Although these and other estimates and assumptions are based on the best available information, actual results could be materially different from these estimates.

In the condensed consolidated income statements, the total revenues reported combine gross revenues for the physical commodities business and net revenues for all other businesses. The subtotal ‘operating revenues’ in the condensed consolidated income statements is calculated by deducting physical commodities cost of sales from total revenues. The subtotal ‘net operating revenues’ in the condensed consolidated income statements is calculated as operating revenues less transaction-based clearing expenses, introducing broker commissions and interest expense. Transaction-based clearing expenses represent variable expenses paid to executing brokers, exchanges, clearing organizations and banks in relation to our transactional volumes. Introducing broker commissions include commission paid to non-employee third parties that have introduced customers to the Company. Net operating revenues represent revenues available to pay variable compensation to risk management consultants and traders and direct non-variable expenses, as well as variable and non-variable expenses of operational and administrative employees.

Change in Precious Metals Accounting

The Company engages in trading activities in a variety of physical commodities, including actively trading precious metals whereby the Company provides a full range of trading and hedging capabilities, including OTC products, to select producers, consumers, and investors. In the Company’s precious metals trading activities, it acts as a principal, committing its own capital to buy and sell precious metals on a spot and forward basis.

On April 10, 2015 (the “transfer date”), the Company transitioned the portion of its precious metals business conducted through its unregulated domestic subsidiary, INTL Commodities Inc., to its United Kingdom based broker-dealer subsidiary, INTL FCStone Ltd. INTL FCStone Ltd is regulated by the Financial Conduct Authority (“FCA”), the regulator of the financial services industry in the United Kingdom.

In anticipation of the transfer of the precious metals business, INTL Commodities Inc. liquidated all of its precious metals inventory as of the transfer date. Subsequent to the transfer, precious metals inventory held by INTL FCStone Ltd. is measured at fair value, with changes in fair value included as a component of ‘trading gains, net’ on the condensed consolidated income statement, in accordance with U.S. GAAP accounting requirements for broker-dealers. Precious metals inventory held by subsidiaries that are not broker-dealers continues to be valued at the lower of cost or market value.

Prior to the transfer, INTL Commodities Inc. precious metals sales and costs of sales were recorded on a gross basis in accordance with the Revenue Recognition Topic of the Accounting Standards Codification (“ASC”). Subsequent to the transfer, INTL FCStone Ltd. precious metals sales and cost of sales are presented on a net basis and included as a component of ‘trading gains, net’ on the condensed consolidated income statements, in accordance with U.S GAAP accounting requirements for broker-dealers. Precious metals sales and cost of sales for subsidiaries that are not broker-dealers continue to be recorded on a gross basis.

The change had no effect on the Company’s operating revenues, income before tax, or net income. Management has historically assessed the performance of the physical commodities businesses on an operating revenues basis, and continues to do so.

Recent Accounting Pronouncements

In June 2016, the FASB issued new accounting guidance for recognition of credit losses on financial instruments, which is effective January 1, 2020, with early adoption permitted on January 1, 2019. The guidance introduces a new credit reserving model known as the Current Expected Credit Loss (“CECL”) model, which is based on expected losses, and differs significantly from the incurred loss approach used today. The CECL model requires measurement of expected credit losses not only based on historical experience and current conditions, but also by including reasonable and supportable forecasts incorporating forward-looking information and will likely result in earlier recognition of credit reserves. The Company is currently evaluating the impact the new guidance will have on its financial position, results of operations and cash flows.

In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (ASU) 2014-09, “Revenue from Contracts with Customers (Topic 606).” ASU 2014-09 completes the joint effort by the FASB and International Accounting Standards Board (IASB) to improve financial reporting by creating common revenue recognition guidance for GAAP and International Financial Reporting Standards (IFRS). In March 2016, the FASB issued ASU 2016-08, “Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net).” ASU 2016-08 clarifies the implementation guidance on principal versus agent considerations. In April 2016, the FASB issued ASU 2016-10, “Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing.” ASU 2016-10 clarifies the implementation guidance on identifying performance obligations. These ASUs apply to all companies that enter into contracts with customers to transfer goods or services. These ASUs are effective for public entities for interim and annual reporting periods beginning after December 15, 2017. Early adoption is permitted only as of annual reporting periods beginning after December 15, 2016, including interim periods within that reporting period. The Company expects to adopt this guidance starting with the first quarter of fiscal year 2019. Entities have the choice to apply these ASUs either retrospectively to each reporting period presented or by recognizing the cumulative effect of applying these standards at the date of initial application and not adjusting comparative information. The Company is currently evaluating the requirements of these standards and has not yet determined the impact on our condensed consolidated financial statements.

In March 2016, the FASB issued ASU 2016-09, “Compensation – Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting.” ASU 2016-09 simplifies the accounting for share-based payment award transactions including: income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. ASU 2016-09 is effective for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years. Early adoption is permitted. The Company expects to adopt this guidance starting with the first quarter of fiscal year 2018. The Company is currently evaluating the requirements of ASU 2016-09 and has not yet determined the impact on our condensed consolidated financial statements.

In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), which supersedes ASC 840, Leases. This ASU is based on the principle that entities should recognize assets and liabilities arising from leases. The ASU does not significantly change the lessees’ recognition, measurement and presentation of expenses and cash flows from the previous accounting standard. The ASU’s primary change is the requirement for entities to recognize a lease liability for payments and a right of use asset representing the right to use the leased asset during the term on operating lease arrangements. Lessees are permitted to make an accounting policy election to not recognize the asset and liability for leases with a term of twelve months or less. Lessors’ accounting under the ASC is largely unchanged from the previous accounting standard. In addition, the ASU expands the disclosure requirements of lease arrangements. Lessees and lessors will use a modified retrospective transition approach, which includes a number of practical expedients. This guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. The Company expects to adopt this guidance starting with the first quarter of fiscal year 2020. The Company has not determined the potential effects on the condensed consolidated financial statements.

In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments--Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. ASU No. 2016-01 addresses the recognition, measurement, presentation and disclosure of financial assets and liabilities. The guidance primarily affects the accounting for equity investments, financial liabilities under the fair value option and the presentation and disclosure requirements for financial instruments. In addition, the guidance clarifies the valuation allowance assessment when recognizing deferred tax assets resulting from unrealized losses on available-for-sale debt securities. This guidance is effective for the Company in the first quarter of fiscal 2019, and early adoption is not permitted, with certain exceptions. The amendments are required to be applied by means of a cumulative-effect adjustment on the balance sheet as of the beginning of the fiscal year of adoption. The Company is currently assessing the impact, if any, the guidance may have upon adoption.

In April 2015, the FASB issued ASU No. 2015-03, Interest – Imputation of Interest (Subtopic 835-30). ASU 2015-03 requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability. In June 2015, the FASB issued ASU 2015-15 as an amendment to this guidance to address the absence of authoritative guidance for debt issuance costs related to line-of-credit arrangements. The SEC staff stated that they would not object to an entity deferring and presenting debt issuance costs as an asset and subsequently amortizing the deferred debt issuance costs ratably over the term of the line-of-credit arrangement, regardless of whether there are any outstanding borrowings on the line-of-credit arrangement. The ASU is effective for public entities for annual periods beginning after December 15, 2015, and interim periods within those annual reporting periods. Early adoption is permitted for financial statements that have not been previously issued. The guidance will be applied on a retrospective basis. The Company expects to adopt this guidance starting with the first quarter of fiscal year 2017. The adoption of this standard is not expected to have a material impact on the condensed consolidated financial statements.